Ch. 6.3, 6.4 & 6.5Energy & Enzymes

_______________________required to start the reaction

energy level of reactants

energy content

ofmolecules

energy level of products

progress of reaction

An _____________________ reaction Sparks ignite gas

high

low

6.2 All Chemical Reactions Require Activation Energy to Begin

https://www.youtube.com/watch?v=p-27I_osoaw&feature=related (History Lesson on Endo and Exo)http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/chemreac/energychangesrev1.shtml (ex of rxn)

(b) An exergonic reaction

6.3 How is Energy Transported Within Cells organisms powered by chemical energy supplied by ____________ breakdown of glucose energy transferred to _____________________________(i.e. ATP)

charged by exergonic rxns and drive endergonic rxns (i.e. rechargeable batteries ATP recycled approx. 1,400X/day (marathon runner uses a lb.

of ATP/min

Dehydration synthesis uses energy when making ATP

from ADP.

_________________________– energy carrier molecules that ______________energetic electrons & H+ ions

donate high-energy electrons to other molecules NADH, FADH2

Coupled Reactions Link Exergonic with Endergonic Reactions

_____________reaction - exergonic rxns provide energy needed to __________endergonic rxns

___________________ - plants use sunlight (____gonic) to drive _______gonic synthesis of high-energy glucose molecules from lower-energy reactants (CO2 + H2O)

________________ – organisms break down glucose into CO2 + H2O(_____gonic) to drive synthesis of proteins, amino acids (_____gonic)

energy is always __________________every time it is transformed energy released (exergonic) must always exceed energy needed (endergonic)

https://www.youtube.com/watch?v=7IqgrcBkGRU

activation energy determines the ________ at which a reaction occurs https://www.youtube.com/watch?v=VbIaK6PLrRM

Blue = exothermicGreen = endothermic

some important chemicalreactions are too slow or have a high activation energy

6.4 How Do Enzymes Promote Biochemical Reactions?

reactants

reactants

exothermic

_____________ – substances that __________rates of chemical reactions w/o being used up or permanently altered

https://www.youtube.com/watch?v=hNl5WYSM5DE (Elephant Toothpaste)https://www.youtube.com/watch?v=v9ju2rZ8YmM (how catalytic converters work – 10 min)

Enzymes are Biological Catalysts not advantageous to speed up dozens of rxns at once; so it is a _________________

_______________– natural catalysts (mostly proteins)

each catalyzes only a few types of rxns (most only catalyze 1 with specific molecules)

exergonic & endergonic rxns can be catalyzed

ATP synthase + ATPasehttps://www.youtube.com/watch?v=W3KxU63gcF4 (ATP Synthase)

Structure of Enzymes Allows Them to Catalyze Specific Reactions

____________ of enzyme _______________ its ____________ (just like proteins) structure – determined by a.a. sequence/twisted/folded

shape and charges of a.a. that form active site determines what molecules can enter (amylase starch not cellulose; pepsin & trypsin) some catalyze tens of thousands of rxns/sec and some act much slower https://www.youtube.com/watch?v=lfuOQZJ_MIM (firefly)

Enzymes, Like All Catalysts, Lower Activation Energy

reactions occur in_____; each step catalyzed by different enzymes ____________activation energy overall reaction can occur at

body temp

https://www.youtube.com/watch?v=r1ryDVgx0zw

https://www.youtube.com/watch?v=tI69AVRW0DU (related to digestion)

How Are Enzymes Regulated?

metabolism – sum of all the ________________________in a cell

metabolic pathways – reactions that are linked together - ________________ step acts as the ________________________ step

i.e. _______________ (synthesis of high energy molecules i.e. glucose)

i.e. glycolysis (begins breakdown of glucose)

Initial reactant Intermediates End products

PATHWAY 1

PATHWAY 2

enzyme 1 enzyme 2 enzyme 3 enzyme 4

enzyme 5 enzyme 6https://www.youtube.com/watch?v=l_vvz5fD00M – photo & resp.

Cells must regulate metabolic pathways by controlling ____ produced.

a) type of enzymesb) quantity of enzymesc) activity levels of enzymes

for a given ____________ of enzyme, as substrate levels increase, the rxn rate ______________ until active sites of all enzymes are being continuously occupied by new substrate

________that code for enzymes can turn _____________ - marathon runners & high-carb meals b4 competitions- glucose enters blood & triggers metabolic rxns (i.e.

pancreas releases insulin) - insulin turns on genes that code for 1st enzyme in pathway

that breaks down glucose

Some enzymes only synthesized at ________________ in organisms life (i.e. lactase)

some enzymes are synthesized in _______________ and then activated when needed (i.e. protein digesting pepsin & trypsin – work best in acidic conditions)

http://lgfl.skoool.co.uk/content/keystage3/biology/pc/learningsteps/PAELC/launch.html

Enzyme Activity May be Controlled by Competitive or Noncompetitive Inhibition

Reactions ______________ by competitive inhibition and noncompetitive inhibition to prevent 1) substrates from being _________ and 2) producing _________________ product

____________________ inhibition: substance that is not the enzyme’s normal substrate can _________________to active site of enzyme (competing for a spot)

- structural similarities

i.e. _________________________ (block active site of acetylcholinesterase; excess acetylcholine overstimulates muscles causing paralysis) https://www.youtube.com/watch?v=-gIqZ8IxctE

i.e. _______________________ inhibits synthesis of bacteria cell walls; ________________________________ inhibits synthesis of molecules that contribute to swelling, pain, fever.

____________________ inhibition: molecule binds to a site on enzyme different from active site; ___________________; enzyme less able to catalyze rxn

https://www.youtube.com/watch?v=PILzvT3spCQ (short comparison)

_____________________: _______________________ inhibition where enzymes ___________ easily between 2 different ________ that either activate or inhibit the enzyme (i.e. ADP)

https://www.youtube.com/watch?v=d5fDEUhjo-M

___________________: form of ________________ regulation; causes metabolic pathways to ______________________________ when its concentration reaches an optimal level (thermostat)

https://www.youtube.com/watch?v=DHZtOKyMPRY (feedback inhibition)

As levels of isoleucine rise,isoleucine binds to the regulatorysite on enzyme 1, inhibiting it

intermediates

enzyme 1 enzyme 2 enzyme 3 enzyme 4 enzyme 5

enzyme 1

isoleucine

isoleucine(end product)

threonine(initial

reactant)

Activity of Enzymes is Influenced by Their ____________________

enzymes have a narrow range of conditions (_________________) in which they function optimally (H-bonds btwn polar a.a.)

_______________: when enzymes lose 3-D structure required to function properly

human cellular enzymes work best around pH 7.4; human digestive enzymes work best around pH 2

__________________ affects rate of enzyme catalyzed reactions (_____________ by _______________ temps; ________________ by ________________ temps)

http://lgfl.skoool.co.uk/viewdetails_ks3.aspx?id=452

For pepsin, maximumactivity occurs atabout pH 2

For most cellularenzymes, maximumactivity occursat about pH 7.4

For trypsin, maximumactivity occurs atabout pH 8

rate of

reaction

Effect of pH on enzyme activitypH

106543210 7 8 9

fast

slow

For most human enzymes,maximum activity occursat about 98.6-F (37-C)

rate of

reaction

fast

slow

Effect of temperature on enzyme activitytemperature

60 (-C)0 4020140 (-F)32 68 104